of baden



Aug. 6, 1929. E. ZUBLER TURBINE BLADE LACING Filed Aug' 29. 1927 Patented Aug. 6, 1929.

UNITED STATES PATENT OFFICE.

ERNST ZUBLER, OFy BADEN, SWITZERLAND, ASSIGNOR TO AKTIENGESELLSCHAFT, BROWN IBOVERI & CIE., 0F BADEN, SWITZERLAND, A JOINT-STOCK COMPANY 0F SWITZERLAND.

TURBINE-BLADE LACTNG.

Application filed August 29, 1927, Serial No. 216,260, and n- Germany August 30, 1926.

rl'his invention relates t0 the construction of steam turbines and the like, and pertains particularly to an arrangement for connecting a binding or lacing wire to the blades.

The general object of the invention is the provision 0f a construction which will be effective to increase the security of the connection between the blades and the lacing wire and which may be applied with facility and without requiring special forming or fitting of the respective members to make the joints.

Another object is the provision of a construction which is effective to obtain a secure connection between the blades and the binding wire by means of solder, even when either or both of the connected members are made of rustless steel.

Other and further objects of the invention will be pointed out or indicated hereinafter or will be apparent to one skilled in the art upon an understanding of the invention or its employment in practice.

In the drawing forming a part of this specification I illustrate one structural form which the invention may take, but it is to be understood that this is presented by way of example only, as the invention, within the scope of the appended claims, may be embodied in other specific forms. In said drawinfr Iig. 1 is a detail, showing in side elevation a marginal portion of a rotor disc of a steam turbine with a number of blades mounted thereon.

Fig. 2 is a detail showing a face elevation of a portion of a blade with a binding wire pass ing therethrough, before the permanent connection of the wire to the blade, and

Fig. 3 is a detail in the nature of a section on line 3-3 of Fig'. 2, on an enlarged scale, with the connection completed.

It has been a customary practice heretofore to connect the outer end portions of blades in steam turbines with a wire binding or lacing for the purpose of increasing the strength and stiffness of the blades in the row, or for effecting necessary adjustments in their natural period of vibration. In order to accomplish these objects, it is necessary that a good connection be made between the binding wire and blades. I-Ieretofore it has been possible to obtain secure joints by connecting the blades to the wire by brazing or hard soldering. TWhen the blades are made of rustless steel, however, difficulties have been in* volved in obtaining satisfactory brazed j oints, owing'to the fact that the solder does not unite readily and securely with such metal. The present invention provides an arrangement whereby the desired result may be 0btained in such instances.

As represented in the drawing, the reference numeral l0 designates a portion of a rotor disc in which the blades l1 are mounted, said blades being connected at an appropriate location by a binding or lacing wire 14 which is threaded through apertures in the blades. For the purpose of obtaining a rigid connection between the wire and the respective blades, I employ a fillet member l5 and a suitable solder `1G, such as a silver solder. The fillet members illustrated are in the form of rings, which may be made advantageously of brass or copper wire, and which are placed on the ybinding' wire against the faces of the blades. The solder is then applied to the fillet members and to the adjacent surfaces of the blade and binding wire, with a suitable flux in the customary fashion. Because of the presence of the fillet members in proximity to the blade and wire surfaces on which it is desired to form the braZe, and because of the readiness with which the solder unites with the material of the fillet members, an ample fillet of the solder may be built up quite readily in contact with the blade and wire. This has a two-fold effect. In the first place, it increases the area of the solder joint and enables the solder to take to the material of the blade and the wire with much greater readiness and security. In the second place, the increased mass of the joint exercises a more pronounced effect in altering the natural period of vibration of the blade. When the fillets at opposite sides of the blade are connected through the Wire-receiving aperture in the blade by a portion 1G:L of the solder, the

joint is rendered particularly secure. It is important, to secure the best results, that the fillet members be made of a material with which the selected solder unites quite readily. l/Vhile I have shown the fillet members as of circular cross-section, it will be understood that they may be of other forms.

`What I claim is:

l. In a turbine, the combination with a blade and a binding wire associated with surd face portions in angular relationship7 of a lillet member arranged in the angle between the surfaces and a Connection of solder built up in the angle about the fillet member and adhering to the same and to the blade and wire.

2. In apparatus of the character described, a blade pr vided with an opening extending,` transversely therethrough, a supporting` element for said blade extending through said opening and beingof smaller Cross-sectional area than the area of said opening, solder applied as a'unitary mass to said blade at said opening thereof and to said supporting element therefor and operating,` to rigidly conneet the saine, said solder being disposed in and substantially filling the space between said blade and said element and extending outwardly along said element beyond opposite faces of said blade and extendingradially outwardly from said element over the opposite adjacent face portions of said blade, and fillet members disposed about said element on opposite sides of said blade and embedded in said solder.

ln testimony whereof I have hereunto subscribed my name this 16th day of August, A. D. 199.7, at Zurich, Switzerland.

ERNST ZUBLER. 

